Plasma current (I_p).

In a tokamak, the plasma itself carries a large electric current that helps confine and heat it. It is central to the breeder — and, tellingly, entirely absent from the burner.

What it does

Confines and heats a tokamak plasma

Breeder current

9.86 MA (≈ ⅔ of ITER's 15 MA)

Burner current

None — open field lines, no toroidal current

Consequence

The burner cannot disrupt

A tokamak drives a large toroidal current through its plasma; that current generates part of the confining field and heats the gas. The Kronos breeder runs 9.86 MA — about two-thirds of ITER's 15 MA — in a machine a fraction of ITER's size, reaching its performance through high field and power density rather than scale.

The burner is fundamentally different: as an open, linear machine it carries no toroidal plasma current. That absence is not a detail — it is why the burner cannot disrupt, removing an entire failure mode that tokamaks must engineer against.